Technology always comes from human nature, so human machine interfaces of electronic devices are continuously developed in order to provide an improved or more intuitive experience of using the electronic devices to users. Traditional punched cards were used in the past and gradually evolved into well-known keyboard/mouse or game controllers nowadays. Recently, touch panels, somatosensory input devices and brainwave controllers are created. Technical personnel are devoted to providing a simple and intuitive input method to users. Briefly speaking, human motion input is a new technique highly anticipated in the field of human machine interface.
Take gesture input devices as an example. In general, gesture input devices operate based on image recognition technologies. Because the background images are complicated and infrared cameras would be interfered by the sunlight having complicated wavelengths, gesture input devices or somatosensory input devices can not be utilized outdoors. Especially for wearable devices which are more intuitive and portable. Take Google glass as an example. Since human motion input interfaces can not be utilized in Google glass, it is necessary for Google glass to use voice-controlled methods as an input interface.
On the other hand, image recognition technologies rely on image capturing module for obtaining input information. Currently, in the methods of gesture recognition based on a built-in camera, the user's hand needs to stay within the range that the built-in camera could reach. In this condition, it results in controlling actions which are not smooth extremely. Moreover, even though wearable devices can be worn outdoors, the wearable devices can not be controlled under the sunlight because of the limitation of the present IR image recognition technology. The voice-controlled methods are ineffective outdoors because of background noises.